As others mentioned, VP8, VP9 and AV1 all are patent encumbered - they just happen to have licenses that are royalty-free and as someone mentioned, include retaliation clauses which help fighting off submarine patents - but that's essentially a possibly high-stakes game of chicken.
While they are patent-encumbered in the strictest sense of the word, they are not as aggressively licensed as H.266 -- which is what GP was lamenting. Licensing H.266 under the GPL(v3) wouldn't erase the existence of the patents and it would still be "patent-encumbered" in the same sense that VP8/9 and AV1 are.
And retaliation clauses are present in basically every free software license that has clauses dealing with patents (including Apache-2.0).
GPL is the example GP used, which is why I referenced it. It's not really important what free software license it would be (though GPLv3 does have an entire section (s11) which is all about patents -- that's why it's compatible with Apache-2.0).
